Formation and deposition of sputtered nanoscale particles in cigarette manufacture

ABSTRACT

Nanoscale particles are formed and deposited in situ on tobacco cut filler, cigarette paper and/or cigarette filter materials by physical vapor deposition. The nanoscale particles are capable of acting as an oxidant for the conversion of carbon monoxide to carbon dioxide and/or as a catalyst for the conversion of carbon monoxide to carbon dioxide.

This application is a divisional application of U.S. application Ser.No. 10/972,205 entitled FORMATION AND DEPOSITION OF SPUTTERED NANOSCALEPARTICLES IN CIGARETTE MANUFACTURE, filed on Oct. 25, 2004 now U.S. Pat.No. 8,051,859, which claims priority under 35 U.S.C. §119(e) to U.S.Provisional Application No. 60/514,553, filed Oct. 27, 2003, the entirecontent of each is hereby incorporated by reference.

BACKGROUND

A variety of gaseous species may be contained in cigarette smoke, suchas polynuclear aromatic hydrocarbons (PAHs), heterocyclic compounds,hydrogen cyanide (HCN), nitric oxides (NO_(x)) and carbon monoxide (CO).Conventional techniques, such as normal dilution, filtration, orselective filtration are not completely satisfactory for reducing suchconstituents in mainstream cigarette smoke.

Despite the developments to date, there is interest in improved and moreefficient methods and compositions for reducing the amount of carbonmonoxide in the mainstream smoke of a cigarette during smoking.Preferably, it should be possible to catalyze and/or oxidize carbonmonoxide not only in the filter region of the cigarette but also alongthe entire length of the cigarette during smoking.

SUMMARY

A preferred embodiment relates to a method that uses physical vapordeposition to deposit nanoscale particles on a substrate. The substratemay comprise tobacco cut filler, cigarette paper and/or cigarette filtermaterial. The method comprises the steps of (i) supporting the substratein a chamber having a target; (ii) bombarding the target with energeticions to form nanoscale particles; and (iii) depositing the nanoscaleparticles on the substrate.

A further embodiment relates to a method of making a cigarette,comprising the steps of (i) depositing nanoscale particles directly onat least one of tobacco cut filler and cigarette paper; (ii) providingthe tobacco cut filler to a cigarette making machine to form a tobaccocolumn; and (iii) placing the cigarette paper around the tobacco rod toform a tobacco rod of a cigarette, wherein the nanoscale particles aredeposited by physical vapor deposition.

According to yet a further embodiment, tobacco cut filler comprisesnanoscale particles wherein the nanoscale particles are formed anddeposited directly on the tobacco cut filler by physical vapordeposition. In a still further embodiment, a cigarette comprises tobaccocut filler and cigarette paper, wherein at least one of the cut fillerand cigarette paper comprises nanoscale particles formed and depositeddirectly on the at least one of tobacco cut filler and cigarette paperby physical vapor deposition.

Preferably the nanoscale particles are capable of acting as an oxidantfor the conversion of carbon monoxide to carbon dioxide and/or as acatalyst for the conversion of carbon monoxide to carbon dioxide. Thenanoscale particles can be deposited in an amount effective to reducethe ratio in mainstream smoke of carbon monoxide to total particulatematter by at least 10%. Preferably, the nanoscale particles compriseless than about 10% by weight of the substrate.

The nanoscale particles may comprise B, Al, Si, Ti, Fe, Co, Ni, Cu, Zn,Ge, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Sn, Ce, Hf, Ta, W, Re, Os, Ir, Pt, Auand mixtures thereof. Thus, the nanoscale particles may comprise a metalor a metal oxide such as iron oxide. The nanoscale particles may becrystalline or amorphous. Preferably the nanoscale particles have anaverage particle size of less than about 50 nm, more preferably lessthan about 10 nm.

According to a preferred embodiment, the chamber is a vacuum chamber.The physical vapor deposition can be carried out in an inert atmospheresuch as an argon atmosphere, or the physical vapor deposition cancarried out in an atmosphere comprising a reactive gas such as anatmosphere comprising hydrogen, air, oxygen, water vapor or nitrogen.

The physical vapor deposition can be carried out at a pressure ofgreater than about 1×10⁻⁴ Torr such as a pressure of about atmosphericpressure. The temperature of the substrate during the deposition can befrom about −196° C. to 100° C., preferably from about 25° C. to 100° C.The temperature of the substrate can be lower by flowing liquid nitrogenat the base of the support material. Preferably the substrate issupported at a distance of from about 2 to 20 cm from the target.

The physical vapor deposition may comprise laser ablation or sputteringsuch as radio frequency sputtering or magnetron sputtering. According toa preferred embodiment, the physical vapor deposition comprises radiofrequency sputtering in a noble gas plasma.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a sputter deposition apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following describes methods of forming and depositing nanoscaleparticles directly on substrates such as tobacco cut filler, cigarettepaper and/or cigarette filter materials. Nanoscale particles are formedand deposited on the substrates by physical vapor deposition (PVD). Themethod comprises the steps of (i) supporting the substrate in a chamberhaving a target; (ii) bombarding the target with energetic ions to formnanoscale particles; and (iii) depositing the nanoscale particles on thesubstrate.

A further embodiment relates to a method of making a cigarette,comprising the steps of (i) depositing nanoscale particles directly onat least one of tobacco cut filler and cigarette paper; (ii) providingthe tobacco cut filler to a cigarette making machine to form a tobaccocolumn; and (iii) placing the cigarette paper around the tobacco columnto form a tobacco rod of a cigarette, wherein the nanoscale particlesare deposited by physical vapor deposition.

According to yet a further embodiment, tobacco cut filler comprisesnanoscale particles wherein the nanoscale particles are formed anddeposited directly on the tobacco cut filler by physical vapordeposition. In a still further embodiment, a cigarette comprises tobaccocut filler and cigarette paper, wherein at least one of the cut fillerand cigarette paper comprises nanoscale particles formed and depositeddirectly on the at least one of tobacco cut filler and cigarette paperby physical vapor deposition.

The nanoscale particles, which are capable of acting as an oxidant forthe conversion of carbon monoxide to carbon dioxide and/or as a catalystfor the conversion of carbon monoxide to carbon dioxide, can reduce theamount of carbon monoxide in mainstream smoke during smoking.

Physical vapor deposition includes sputter deposition and laser ablationof a target material. Sputter deposition is a preferred method. With PVDprocesses, material from a source (or target) is removed from the targetby physical erosion by ion bombardment and deposited on a surface of asubstrate. The target is formed of (or coated with) a consumablematerial to be removed and deposited, i.e., target material.

Sputtering is conventionally implemented by creating a glow dischargeplasma over the surface of the target material in a controlled pressuregas atmosphere. Energetic ions from the sputtering gas, usually achemically inert noble gas such as argon, are accelerated by an electricfield to bombard and eject atoms from the surface of the targetmaterial. By energetic ions is meant ions having sufficient energy tocause sputtering of the target material.

If the density of the ejected atoms is sufficiently low, and theirrelative velocities sufficiently high, atoms from the target materialtravel through the gas until they impact the surface of the substratewhere they can coalesce into nanoscale particles. If the density of theejected atoms is sufficiently high, and their relative velocitiessufficiently small, individual atoms from the target can aggregate inthe gas phase into nanoscale particles, which can then deposit on thesubstrate.

Without wishing to be bound by theory, at a sputtering pressure lowerthan about 10⁻⁴ Torr the mean free path of sputtered species issufficiently long that sputter species arrive at the substrate withoutundergoing many gas phase collisions. Thus, at lower pressures,sputtered material can deposit on the substrate as individual species,which may diffuse and coalesce with each other to form nanoscaleparticles after alighting on the substrate surface. At a higherpressures, such as pressures above about 10⁻⁴ Torr, the collisionfrequency in the gas phase of sputtered species is significantly higherand nucleation and growth of the sputtered species to form nanoscaleparticles can occur in the gas phase before alighting on the substratesurface. Thus, at higher pressures, sputtered material can formnanoscale particles in the gas phase, which can deposit on the substrateas discrete nanoscale particles.

There are several different types of apparatus that can be used togenerate a glow discharge plasma for sputtering. In a DC diode system,there are two electrodes. A positively charged anode supports thesubstrate to be coated and a negatively charged cathode comprises thetarget material. In the DC diode system, sputtering of the target isachieved by applying a DC potential across the two electrodes.

In a radio-frequency (RF) sputtering system, an AC voltage (rather thana DC voltage) is applied to the electrodes. Advantageously, an RFsputtering system can be used to sputter dielectric materials ormaterials that form an insulating layer such as a native oxide. In bothDC and RF sputtering, most secondary electrons emitted from the targetdo not cause ionization events with the sputter gas but instead arecollected at the anode. Because many electrons pass through thedischarge region without creating ions, the sputtering rate of thetarget is lower than if more electrons were involved in ionizingcollisions.

One known way to improve the efficiency of glow discharge sputtering isto use magnetic fields to confine electrons to the glow region in thevicinity of the cathode/target surface. This process is termed magnetronsputtering. The addition of such magnetic fields increases the rate ofionization. In magnetron sputtering systems, deposition rates greaterthan those achieved with DC and RF sputtering systems can be achieved byusing magnetic fields to confine the electrons near the target surface.

A method of depositing nanoscale particles via sputtering is provided inconjunction with the exemplary sputtering apparatus depicted in FIG. 1.Apparatus 20 includes a sputtering chamber 21 having an optionalthrottle valve 22 that separates the chamber 21 from an optional vacuumpump (not shown). A pressed powder target 23 such as an iron oxidetarget is mounted in chamber 21. Optional magnets 24 are located on thebackside of target 23 to enhance plasma density during sputtering. Thesputtering target 23 is electrically isolated from the housing 29 andelectrically connected to a RF power supply 25 through an impedancematching device 26. Substrates 27, such as tobacco cut filler, cigarettepaper or tobacco filter material, are mounted on a substrate holder 28,which is electrically isolated from the housing 29 by a dielectricspacer 30. The housing 29 is maintained at a selected temperature suchas room temperature. The substrate holder 28 can be RF biased for plasmacleaning using an RF power supply 31 connected through an impedancematching device 32. The substrate holder 28 is also provided withrotation capability 33.

Referring still to FIG. 1, the reactor chamber 21 contains conduits 34and 35 for introducing various gases. For example, argon could beintroduced through conduit 34 and, optionally, oxygen through conduit35. Gases are introduced into the chamber by first passing them throughseparate flow controllers to provide a total pressure of argon andoxygen in the chamber of greater than about 10⁻⁴ Torr.

In order to obtain a reactive sputtering plasma of the gas mixture, anRF power density of from about 0.01 to 10 W/cm² can be applied to thetarget 23 throughout the deposition process. Pressure in the chamberduring physical vapor deposition can be between about 10⁻⁴ Torr to 760Torr. The substrate temperature can be between about −196° C. and 100°C. A temperature gradient can be maintained between the target and thesubstrate during the deposition by flowing a cooling liquid such aschilled water or liquid nitrogen through the substrate support.

Nanoscale particles may be formed and deposited on a substrate using anablation process, wherein a suitable high energy source such as a laseris aimed at a target under conditions sufficient to release individualparticles from the target. Lasers include, but are not limited to,Nd-YAG lasers, ion lasers, diode array lasers and pulsed excimer lasers.Advantageously, ablation such as laser ablation can be performed at orabove atmospheric pressure without the need for vacuum equipment. Thus,the nanoscale particles may be simultaneously formed and deposited on asubstrate that is maintained at ambient temperature and atmosphericpressure during the deposition process.

An apparatus for ablative processing includes a chamber in which atarget material is placed. An external energy source, such as a pulsedexcimer laser, enters the chamber through a window, preferably quartz,and interacts with target. Alternatively, the energy source can beinternal, i.e., positioned inside the chamber.

In an ablative process, a region of the target absorbs incident energyfrom the energy source. This absorption and subsequent heating of thetarget causes target material to ablate from the surface of the targetinto a plume of atomic and nanometer-scale particles. The substratematerial may be supported on a substrate holder or, because a laserablation process can be carried out at atmospheric pressure, passedthrough the coating chamber on a moving substrate holder such as aconveyor belt operated continuously or discontinuously to provide adesired amount of deposited nanoscale particles on the substratematerial.

As is well known in the art, energetic ions can also be provided in theform of an ion beam from an accelerator, ion separator or an ion gun. Anion beam may comprise inert gas ions such as neon, argon, krypton orxenon. Argon is preferred because is can provide a good sputter yieldand is relatively inexpensive. The energy of the bombarding inert gasion bean can be varied, but should be chosen to provide a sufficientsputtering yield. The ion beam can be scanned across the surface of thetarget material in order to improve the uniformity of target wear.

The introduction of reactive gases into the chamber during thedeposition process allows material sputtered or ablated from the targetto combine with such gases to obtain compound nanoscale particles. Thus,in reactive PVD the sputtering gas includes a small proportion of areactive gas, such as hydrogen, air, oxygen, water vapor, nitrogen,etc., which reacts with the atoms of the target material to form metalcompound particles such as hydride, oxide and/or nitride nanoscaleparticles.

Compound nanoscale particles can also be deposited on a substrate viathe sputtering of the corresponding compound (e.g., hydride, oxide ornitride) target. For example, iron oxide nanoscale particles may bedeposited by sputtering an iron target in the presence of oxygen and/orby sputtering an iron oxide target.

The microstructure of the nanoscale particles can be controlled usingphysical vapor deposition. Density, phase distribution and the extentand morphology of crystalline (versus amorphous) phases can becontrolled by varying, for example, the deposition pressure, ion energyand substrate temperature.

The nanoscale particles can comprise B, Al, Si, Ti, V, Cr, Fe, Co, Ni,Cu, Zn, Ge, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Sn, Ce, Hf, Ta, W, Re, Os,Ir, Pt, Au, as well as hydrides, oxides, nitrides and mixtures thereof.

As discussed above, with sputtering the substrate is typically placedproximate to the cathode. With sputtering and ablative processes, thesubstrate is placed within sputtering proximity of the target, such thatit is in the path of the sputtered or ablated target atoms and thetarget material is deposited on the surface of the substrate.

By regulating the deposition parameters, including background gas,pressure, substrate temperature and time, it is possible to preparecigarette components such as tobacco cut filler, cigarette paper and/orcigarette filter material that comprise a loading and distribution ofnanoscale particles thereon effective to reduce the amount of carbonmonoxide in mainstream smoke.

Preferably, the nanoscale particles are deposited in an amount effectiveto reduce the ratio in mainstream smoke of carbon monoxide to totalparticulate matter (e.g., tar) by at least 10%, more preferably by atleast 25%. Preferably, the nanoscale particles comprise less than about10% by weight of the substrate, more preferably less than about 5% byweight of the substrate.

The PVD process is stopped when there is still exposed substratesurface. That is, the PVD method does not build up a continuous layerbut rather forms clusters of discrete nanoscale particles that aredistributed over the substrate surface. During the process, new clustersform and existing clusters grow.

Advantageously, physical vapor deposition allows for dry, solvent-free,simultaneous formation and deposition of nanoscale particles understerile conditions.

“Smoking” of a cigarette means the heating or combustion of thecigarette to form smoke, which can be drawn through the cigarette.Generally, smoking of a cigarette involves lighting one end of thecigarette and, while the tobacco contained therein undergoes acombustion reaction, drawing the cigarette smoke through the mouth endof the cigarette. The cigarette may also be smoked by other means. Forexample, the cigarette may be smoked by heating the cigarette and/orheating using electrical heater means, as described in commonly-assignedU.S. Pat. Nos. 6,053,176; 5,934,289; 5,591,368 or 5,322,075.

The term “mainstream” smoke refers to the mixture of gases passing downthe tobacco rod and issuing through the filter end, i.e. the amount ofsmoke issuing or drawn from the mouth end of a cigarette during smokingof the cigarette.

In addition to the constituents in the tobacco, the temperature and theoxygen concentration are factors affecting the formation and reaction ofcarbon monoxide and carbon dioxide. The total amount of carbon monoxideformed during smoking comes from a combination of three main sources:thermal decomposition (about 30%), combustion (about 36%) and reductionof carbon dioxide with carbonized tobacco (at least 23%). Formation ofcarbon monoxide from thermal decomposition, which is largely controlledby chemical kinetics, starts at a temperature of about 180° C. andfinishes at about 1050° C. Formation of carbon monoxide and carbondioxide during combustion is controlled largely by the diffusion ofoxygen to the surface (k_(a)) and via a surface reaction (k_(b)). At250° C., k_(a) and k_(b), are about the same. At 400° C., the reactionbecomes diffusion controlled. Finally, the reduction of carbon dioxidewith carbonized tobacco or charcoal occurs at temperatures around 390°C. and above.

During smoking there are three distinct regions in a cigarette: thecombustion zone, the pyrolysis/distillation zone, and thecondensation/filtration zone. While not wishing to be bound by theory,it is believed that the nanoscale particles can target the variousreactions that occur in different regions of the cigarette duringsmoking.

First, the combustion zone is the burning zone of the cigarette producedduring smoking of the cigarette, usually at the lighted end of thecigarette. The temperature in the combustion zone ranges from about 700°C. to about 95° C., and the heating rate can be as high as 500°C./second. Because oxygen is being consumed in the combustion of tobaccoto produce carbon monoxide, carbon dioxide, water vapor and variousorganic compounds, the concentration of oxygen is low in the combustionzone. The low oxygen concentrations coupled with the high temperatureleads to the reduction of carbon dioxide to carbon monoxide by thecarbonized tobacco. In this region, the nanoscale particles can convertcarbon monoxide to carbon dioxide via both catalysis and oxidationmechanism. The combustion zone is highly exothermic and the heatgenerated is carried to the pyrolysis/distillation zone.

The pyrolysis zone is the region behind the combustion zone, where thetemperatures range from about 200° C. to about 600° C. The pyrolysiszone is where most of the carbon monoxide is produced. The majorreaction is the pyrolysis (i.e., the thermal degradation) of the tobaccothat produces carbon monoxide, carbon dioxide, smoke components andcharcoal using the heat generated in the combustion zone. There is someoxygen present in this region, and thus the nanoscale particles may actas a catalyst for the oxidation of carbon monoxide to carbon dioxide.The catalytic reaction begins at 150° C. and reaches maximum activityaround 300° C.

In the condensation/filtration zone the temperature ranges from ambientto about 150° C. The major process in this zone is thecondensation/filtration of the smoke components. Some amount of carbonmonoxide and carbon dioxide diffuse out of the cigarette and some oxygendiffuses into the cigarette. The partial pressure of oxygen in thecondensation/filtration zone does not generally recover to theatmospheric level.

According to a preferred method, the nanoscale particles are formed insitu by sputtering and are deposited directly on tobacco cut filler.According to a further embodiment, the nanoscale particles can bedeposited on paper and/or filter materials used to form a cigarette.Nanoscale particles are a novel class of materials whose distinguishingfeature is that their average diameter, particle or other structuraldomain size is below 500 nanometers. The nanoscale particles can have anaverage particle size less than about 100 nm, preferably less than about50 nm, more preferably less than about 10 nm, and most preferably lessthan about 7 nm. At this small scale, a variety of confinement effectscan significantly change the properties of the material that, in turn,can lead to commercially useful characteristics. For example, nanoscaleparticles have very high surface area to volume ratios, which makes themattractive for catalytic applications.

During the conversion of CO to CO₂, the nanoscale particles may becomereduced. For example, nanoscale particles of Fe₂O₃, which may depositedon tobacco cut filler, cigarette paper and/or cigarette filter materialmay be reduced to FeO or Fe during the reaction of CO to CO₂.

Iron oxide is a preferred constituent in the nanoscale particles becauseis has a dual function as a CO catalyst in the presence of oxygen and asa CO oxidant for the direct oxidation of CO in the absence of oxygen. Acatalyst that can also be used as an oxidant is especially useful forcertain applications, such as within a burning cigarette where thepartial pressure of oxygen can be very low.

The nanoscale particles will preferably be distributed throughout thetobacco rod and/or along the cigarette paper or filter portions of acigarette. By providing the nanoscale particles throughout the tobaccorod and/or along the cigarette paper, it is possible to reduce theamount of carbon monoxide drawn through the cigarette, and particularlyat both the combustion region and in the pyrolysis zone.

The nanoscale particles, as described above, may be provided along thelength of a tobacco rod or at discrete locations along the length of atobacco rod. For example, the nanoscale particles can be deposited onloose cut filler tobacco stock or deposited directly on a tobacco columnprior to wrapping cigarette paper around the cigarette column. Thenanoscale particles may be deposited directly on cigarette paper beforeor after the cigarette paper is incorporated into a cigarette.

The amount of the nanoscale particles can be selected such that theamount of carbon monoxide in mainstream smoke is reduced during smokingof a cigarette. Preferably, the amount of the nanoscale particles willbe a catalytically effective amount, e.g., an amount sufficient tooxidize and/or catalyze at least 10% of the carbon monoxide inmainstream smoke, more preferably at least 25%.

One embodiment provides tobacco cut filler comprising nanoscaleparticles wherein the nanoscale particles are formed and depositeddirectly on the tobacco cut filler by physical vapor deposition.

Any suitable tobacco mixture may be used for the cut filler. Examples ofsuitable types of tobacco materials include flue-cured, Burley, Marylandor Oriental tobaccos, the rare or specialty tobaccos, and blendsthereof. The tobacco material can be provided in the form of tobaccolamina, processed tobacco materials such as volume expanded or puffedtobacco, processed tobacco stems such as cut-rolled or cut-puffed stems,reconstituted tobacco materials, or blends thereof. The tobacco can alsoinclude tobacco substitutes.

In cigarette manufacture, the tobacco is normally employed in the formof cut filler, i.e., in the form of shreds or strands cut into widthsranging from about 1/10 inch to about 1/20 inch or even 1/40 inch. Thelengths of the strands range from between about 0.25 inches to about 3.0inches. The cigarettes may further comprise one or more flavorants orother additives (e.g. burn additives, combustion modifying agents,coloring agents, binders, etc.) known in the art.

Another embodiment provides a cigarette comprising tobacco cut fillerand cigarette paper, wherein at least one of the cut filler andcigarette paper comprises nanoscale particles formed and depositeddirectly on the at least one of tobacco cut filler and cigarette paperby physical vapor deposition. A further embodiment provides a method ofmaking a cigarette comprising: (i) depositing nanoscale particlesdirectly on at least one of tobacco cut filler and cigarette paper; (ii)providing the tobacco cut filler to a cigarette making machine to form atobacco column; and (iii) placing the cigarette paper around the tobaccocolumn to form a tobacco rod of a cigarette, wherein the nanoscaleparticles are deposited by physical vapor deposition.

Techniques for cigarette manufacture are known in the art. Anyconventional or modified cigarette making technique may be used toincorporate the nanoscale particles. The resulting cigarettes can bemanufactured to any known specifications using standard or modifiedcigarette making techniques and equipment. Typically, the cut fillercomposition is optionally combined with other cigarette additives, andprovided to a cigarette making machine to produce a tobacco rod, whichis then wrapped in cigarette paper, and optionally tipped with filters.

Cigarettes may range from about 50 mm to about 120 mm in length. Thecircumference is from about 15 mm to about 30 mm in circumference, andpreferably around 25 mm. The tobacco packing density is typicallybetween the range of about 100 mg/cm³ to about 300 mg/cm³, andpreferably 150 mg/cm³ to about 275 mg/cm³.

While various embodiments have been described, it is to be understoodthat variations and modifications may be resorted to as will be apparentto those skilled in the art. Such variations and modifications are to beconsidered within the purview and scope of the claims appended hereto.

All of the above-mentioned references are herein incorporated byreference in their entirety to the same extent as if each individualreference was specifically and individually indicated to be incorporatedherein by reference in its entirety.

1. A method of making a cigarette, comprising: (i) depositing nanoscaleparticles directly on a substrate selected from the group consisting oftobacco cut filler and cigarette paper; (ii) providing the tobacco cutfiller to a cigarette making machine to form a tobacco column; and (iii)placing the cigarette paper around the tobacco column to form a tobaccorod of a cigarette, wherein the nanoscale particles are deposited byphysical vapor deposition.
 2. The method of claim 1, wherein thenanoscale particles are capable of acting as an oxidant for theconversion of carbon monoxide to carbon dioxide and/or as a catalyst forthe conversion of carbon monoxide to carbon dioxide.
 3. The method ofclaim 1, wherein the nanoscale particles are deposited in an amounteffective to reduce the ratio in mainstream tobacco smoke of carbonmonoxide to total particulate matter by at least 10%.
 4. The method ofclaim 1, wherein the nanoscale particles comprise less than about 10% byweight of the substrate.
 5. The method of claim 1, wherein the nanoscaleparticles comprise B, Al, Si, Ti, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo,Ru, Rh, Pd, Ag, Sn, Ce, Hf, Ta, W, Re, Os, Ir, Pt, Au and mixturesthereof.
 6. The method of claim 1, wherein the nanoscale particlescomprise a metal and/or metal compound.
 7. The method of claim 1,wherein the nanoscale particles comprise iron oxide.
 8. The method ofclaim 1, wherein the nanoscale particles have a crystalline or amorphousstructure.
 9. The method of claim 1, wherein the nanoscale particleshave an average particle size of less than about 50 nm.
 10. The methodof claim 1, wherein the nanoscale particles have an average particlesize of less than about 10 nm.
 11. The method of claim 1, wherein thechamber is a vacuum chamber.
 12. The method of claim 1, wherein thephysical vapor deposition is carried out in an inert atmosphere or in anatmosphere comprising a reactive gas.
 13. The method of claim 1, whereinthe physical vapor deposition is carried out in an atmosphere comprisingargon.
 14. The method of claim 12, wherein the reactive gas is selectedfrom the group consisting of hydrogen, air, oxygen, water vapor,nitrogen and mixtures thereof.
 15. The method of claim 1, wherein thephysical vapor deposition is carried out at a pressure of greater thanabout 1×10⁻⁴ Torr.
 16. The method of claim 1, wherein the physical vapordeposition is carried out at a pressure of about atmospheric pressure.17. The method of claim 1, wherein the substrate is at a temperatureduring the deposition of from about −196 EC to 100 EC.
 18. The method ofclaim 1, wherein the substrate is supported at a distance of from about2 to 20 cm from the target.
 19. The method of claim 1, wherein thephysical vapor deposition comprises laser ablation or sputtering. 20.The method of claim 1, wherein the physical vapor deposition comprisesradio frequency sputtering or magnetron sputtering.
 21. The method ofclaim 1, wherein the physical vapor deposition comprises radio frequencysputtering in a noble gas plasma.
 22. Tobacco cut filler comprisingnanoscale particles wherein the nanoscale particles are formed anddeposited directly on the tobacco cut filler by physical vapordeposition.
 23. The tobacco cut filler of claim 22, wherein thenanoscale particles are capable of acting as an oxidant for theconversion of carbon monoxide to carbon dioxide and/or as a catalyst forthe conversion of carbon monoxide to carbon dioxide.
 24. The tobacco cutfiller of claim 22, wherein the nanoscale particles are deposited in anamount effective to reduce the ratio in mainstream tobacco smoke ofcarbon monoxide to total particulate matter by at least 10%.
 25. Thetobacco cut filler of claim 22, wherein the nanoscale particles compriseless than about 10% by weight of the tobacco cut filler.
 26. The tobaccocut filler of claim 22, wherein the nanoscale particles comprise B, Al,Si, Ti, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Sn, Ce, Hf,Ta, W, Re, Os, Ir, Pt, Au and mixtures thereof.
 27. The tobacco cutfiller of claim 22, wherein the nanoscale particles comprise a metaland/or metal compound.
 28. The tobacco cut filler of claim 22, whereinthe nanoscale particles comprise iron oxide.
 29. The tobacco cut fillerof claim 22, wherein the nanoscale particles have a crystalline oramorphous structure.
 30. The tobacco cut filler of claim 22, wherein thenanoscale particles have an average particle size of less than about 50nm.
 31. The tobacco cut filler of claim 22, wherein the nanoscaleparticles have an average particle size of less than about 10 nm.
 32. Acigarette comprising tobacco cut filler and cigarette paper, wherein atleast one of the cut filler and cigarette paper comprises nanoscaleparticles formed and deposited directly on the at least one of tobaccocut filler and cigarette paper by physical vapor deposition.